1813661 has 4 divisors (see below), whose sum is σ = 1825824. Its totient is φ = 1801500.

The previous prime is 1813639. The next prime is 1813667. The reversal of 1813661 is 1663181.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1813661 - 2⁶ = 1813597 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1813661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1813667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5855 + ... + 6156.

It is an arithmetic number, because the mean of its divisors is an integer number (456456).

2^1813661 is an apocalyptic number.

It is an amenable number.

1813661 is a deficient number, since it is larger than the sum of its proper divisors (12163).

1813661 is a wasteful number, since it uses less digits than its factorization.

1813661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12162.

The product of its digits is 864, while the sum is 26.

The square root of 1813661 is about 1346.7223173320. The cubic root of 1813661 is about 121.9510015544.

The spelling of 1813661 in words is "one million, eight hundred thirteen thousand, six hundred sixty-one".